All videotape cassettes have leaders which are permanently locked to both tape spools. Typically this is accomplished by a plastic clamp which fits into a slot in the tape-winding surface such as the locking piece 5 of FIG. 1 of U.S. Pat. No. 4,213,578. Upon driving the clamp into the slot, the leader is sometimes crimped or otherwise damaged. Even when the leader is not damaged during assembly, it sometimes comes loose when pulled. To guard against this, a metal wedge is often driven into an opening in the clamp. If the leader is off-center or misaligned where it emerges from the clamp, its edge might be folded by a flange of the spool.
U.S. Pat. No.4,213,578 includes FIG. 1 as prior art and shows in FIG. 6 an improved clamp which would involve the same crimping problem even though it may improve resistance to leader pull-out. The patent also shows as prior art other tape clamps and how their pull-out resistance might be improved.
FIGS. 10 and 11 of U.S. Pat. No. 3,826,489 show an audiocassette tape spool comprising two identical hub parts which have mating inclined surfaces that wedge the parts together to grip the end of a tape member between radial surfaces. The assembled parts may then be secured to each other by ultrasonic or other conventional techniques.